Green synthesis of zinc oxide nanoparticles using plantain peel extracts and the evaluation of their antibacterial activity

The synthesis of nanoparticles via the green routes is an established technology for producing nano dimensional materials that are useful in different fields where environmental friendly materials are a major requirement. The present study reports a cost effective, eco-friendly and straightforward approach to synthesize zinc oxide nanoparticles (ZnONPs) using plantain peel extract. The optical, structural and morphological characteristics of the ZnONPs were studied using different techniques. X-ray diffraction analysis confirmed a hexagonal wurtzite structure, whose morphology and particle size, according to the transmission electron microscopy (TEM), was spherical and about 20 nm in size. The antimicrobial potency of the ZnONPs was evaluated using agar well diffusion and broth dilution assays against pathogenic strains of Salmonella enterica, Klebsiella pneumoniae, Bacillus cereus MTCC 430 and Staphylococcus aureus 26923, isolated from beef. The biosynthesized ZnONPs demonstrated good antimicrobial activity with a MIC value of 100 µg/mL for all the test isolates. Based on the results obtained, the antimicrobial efficacy of the nanoparticles against the selected bacteria followed the sequence: S. aureus ˃ B. cereus ˃ K. pneumoniae ˃ S. enterica. The results showed that plantain peels, which are the waste of these fruits, could be helpful for the green synthesis of ZnONPs with good antibacterial efficacy.